A long standing challenge for governments and the commercial space industry is developing an effective means for detecting when an unknown object or target is approaching a space-borne platform, such as a satellite. Detection and identification of targets may be necessary to protect satellites from damage and/or functional degradation. The need for “space situational awareness” is accented by an ever increasing effort to use satellites and other space-borne platforms for more than just observation and communication purposes.
Satellite operations often include a gateway antenna on Earth which establishes an uplink with one or more satellites orbiting the Earth. The satellite may be in a low Earth orbit (LEO), medium Earth orbit (MEO) of a geo-stationary orbit (GEO). The uplink is via a transmitted radio frequency signal which is typically in one of several frequency bands, to include C, X, Ka, and Ku bands. Once the link is established, complex tracking algorithms and hardware ensure the link is not broken as the satellite orbits. If the satellite becomes damaged, however, the link may be broken despite the best efforts of the antenna and tracking subsystems.
A reliable, cost effective means for detecting and identifying an object approaching a satellite, or other space-borne platform, does not exist in the open literature. Detection alone is an inadequate defense mechanism, as an approaching object may or may not be man-made, and it may or may not pose an ultimate threat to the platform. Identification, while certainly preferred, often requires expensive detectors and processors that may occupy more space, and utilize more power, than is available on the platform.
Hence, there is a need for a system for space situational awareness that detects and identifies a target as it approaches a space-borne platform, thereby giving operators a chance to take corrective and/or defensive measures. The system must be able to operate within existing satellite system architectures and envelopes, and it must provide reliable data that can be used in a decision making process.